Swell shade control

ABSTRACT

This invention relates to a swell shade control for use with pipe organs and comprises an actuator means and means for connecting the actuator means to the swell shades such that operation of the actuator means in one direction opens the shades, and operations of the actuator means in the opposite direction closes the shades. A command means transmits a first set of electrical signals to an electrical network, which signals represent a final swell shade position. Means responsive to the position of the swell shades are also provided for transmitting second sets of signals to the electrical network representing the instantaneous positions of the shades. The electrical network includes means for generating control signals depending on how the first and second sets of signals compare, which control signals are used to operate the actuator means in a direction to move the swell shades toward the final position.

United States Patent Bosche, Jr.

[s41 SWELL SHADE CONTROL [72] Inventor: Walwin J; Bosche, Jr., Highland, Ill.

[73] Assignee: The Wicks I Organ Company,

' Highland, Ill.

22 Filed: Nov. 16, 1971 21 Appl.No.: 199,205

Primary Examiner-Richard B. Wilkinson Assistant Examiner-Lawrence R. Franklin Attorney-Rogers, Ezell, Eilers & Robbins Oct. 31, 1972 shades. A command means transmits a first set of electrical signals to an electrical network, which signals represent a final swell shade position. Means responsive to the position of the swell shades are also provided for transmitting second sets of signals to the electrical network representingthe instantaneous positionsof the shades. The electrical network includes means for generating control signals depending on how the first and second sets of signals compare, which control signals are used to operate the actuator the final position.

' means in a direction to move the swell shades toward 14 Claims, 11 Drawing Figures /Zf SHOE GRAY TO 76 com: BINARY /7f fi PLATE ENCODER 1 7 L 1 Dc-Ac /W Am RELAY COMPARATOR I DC-AC 90-9? .RE LAY SWELL SHADE GRAY TO /73 /J3 cope BINARY $7 PLATE ENCODER fi/ AC POWER SOURCE //0 air /73 SWELL SHADE CONTROL SUMMARY OF THE INVENTION This invention relates to a swell shade control'assembly for use with pipe organs and particularly one that is digitally operated to "provide smooth, quiet, .and accurate'control.

It is conventional in the pipe organ art to enclose selected sets of organ pipes in a box usually of wood. This box may be in the form of a compartment built into the wall of the room in which the organ is installed. The front opening of the compartment has swell shades mountedtherein, which are similar to venetian blinds only mounted to rotate about a vertical axis between fully closed and fully opened positions. To some degree.

these shades are used to control the volume and tone of the enclosed pipes and are operated by the organist by means of a foot pedal .control located at the organ console. Means, of course, must be provided for producing degrees of opening or closing of the swell shades corresponding to positions of the foot pedal. Such means must operate quietly, smoothly, precisely, and quickly inasmuch as the organist wants the control to react instantly to his command and yet without detracting from the quality of his music. It is further desirable that such a control be relatively small and easy to install. The

swell shade control of this invention is such a device.

The control of this invention includes an actuating means suitably mounted to the swell shade enclosure. A linkage arrangement connects the actuating means to the'swell shades whereby actuation of the actuating means in one direction 'causesthe swell shades to open and actuation of. the actuating means in the other direction causes the swell shades to close. A first code plate is mounted to the actuating means, the code plate being. digitally coded. A plurality of detectors are also mounted in relation to the code plate to continually deswell shades, signals are sentto the digital network corresponding to a first digital code reading from the first set of detectors and a second digital code reading from the second set of detectors.

The digital network includes a comparator means for comparing these two sets of input signals and for generating one output signal when the first detected signal is greater than the second, and another output 1 signal when the second detected signal is greater than the first. These output signals from the comparator means are used to actuate the actuating means to open or close the swellshades as indicated by the comparator outputs. As the swell shades open or close as indicated, the first code plate moves in relationship to the first set of detectors until they detect the same reading as the second set. When this occurs, the output of the comparator means becomes zero and the actuating means ceases operation.

Because the ratio of sound volume to swell shade opening between the fully closed and fully opened positions is generally logarithmic, requiring relatively large variations in swell shade opening near the fully opened conditionto get a given change in volume'eompared to the variation required near the fully closed condition to get the same change in volume,.the first code plate is coded on. a logarithmic scale. Hence, it is one of the features of this invention that linear actuation of the foot pedal provides logarithmic actuation of theswell shades and a linear change in sound volume.

Several types of actuating means can be used in this invention. In one embodiment the actuating means comprises an electric motor and lead screw, the elec tric motor being operated in either a clockwise or counterclockwise direction as directed by the output signals from thecomparator means. As the lead screw turns in one direction it moves a sliding member so as to open the swell shades, and as the lead screw turns in the opposite direction, it moves the sliding member so as to close the swell shades; y 1

In another embodiment of the invention the actuating means comprises a bellows having air intake and exhaust lines controlled by intake and exhaust valves.

Thesevalves in turn are controlled by electric solenoids operated by the comparator output signals. Means are provided for opening and closing the swell shades in response to operation of the bellows. One output signal from the comparator actuates the intake solenoid and valve to inflate the bellows while the other comparator output signal operates the exhaust solenoid and valve to deflate the bellows to thereby open or close the shades. p

It is also possible to use other types of actuating means to operate the swell shades in response to the comparator output signals including, for example, air' or hydraulic cylinders.

Hence,-it is a primary object of this invention to pro- DESCRIPTION OF THE DRAWINGS FIG. 1 is a front elevational-view of the swell shadecontrol assembly of this invention shown mounted to a swell shade;

FIG. 2 is a plan view of the swell shade control assembly of FIG. 1;

FIG. 3 is a view in section taken along the line 33 of FIG. 1; I

FIG. 4 is a view in section taken along the line 44 of FIG. I; FIG. 5 is a view in section taken along the line S-5 of FIG. 1;

FIG. 6 is an enlarged view in section taken along the line 6-6 of FIG. 1;

FIG. 7 is an enlarged view in section taken along the line 7-7 of FIG. 1; v

FIG. 8 is a plan view of the shoe code plate of this invention;

FIG. 9 is a plan view of the swell shade actuator code plate of this invention;

FIG. is a schematic diagram of the control network of this invention for controlling the operation of the swell shade; and

FIG. 11 is a schematic diagram showing another embodiment of the swell shade control of this invention.

I A DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring primarily to FIGS. 1 and 2 there is shown a swell shade enclosure 10 mounted as is conventional in the art in a wall 11 of a room in which it is installed. The swell shade enclosure 10 includes suitable walls such as a side wall 12 and a bottom wall 13, and a plurality of swell shades 14 and 15 each pivotally mounted in a frontal opening 16 of the swell shade enclosure 10 about centrally located vertical axes 18 and 19. There can be any number of swell shades such as the shades l4 and 15 depending on the size of the swell shade enclosure 10. However, for the purpose of this description, it suffices to show only two such shades.

'A mounting bracket shaped generally asshown in FIG. 4 is mounted to the side wall 12 of the swell shade enclosure 10 by any suitable means such as screws 26. A back edge 27 of the bracket 25 rests against the wall 11. The bracket 25 has a pair of forwardly extending arms 29 and 30 with holes 31 and 32, respectively, to whicha swell shade control assembly 35 of this invention is mounted, as will be explained.

Attached to the swell shades 14 and 15 are generally triangular shaped brackets 37 and 38, respectively,

, each of which has one of its sides 40 suitably connected to the swell shade such that a corner 41 of the bracket is located near the pivotal point 18 or 19 of the swell shade. A connecting rod 43 is pivotally connected to the bracket 37 at a point 44, and to the bracket 38 at a point 45,v whereby movement of the rod 43 in the generally lineal direction causes the brackets 37 and 38 to pivot about the points 44'and 45 to the bracket positions shown by dashed lines. This further causes the swell shades 14 and 15 to pivot about the points 18 and 19 to the open. positions shown by dashed lines. The rod 43 is sufficiently long to pivotally connect to each of the swell shade brackets, there being as many brackets as there are swell shades;

The control assembly 35 includes a motor connected by any suitable means such as nut and bolt assemblies 51 to a motor mounting bracket 52 shaped generally as shown in FIG. 3. The motor bracket 52 has upper and lower holes 53 and 54 in axial alignment with the holes 31 and 32 of the bracket 25. The shaft of the motor 50 is connected to a lead screw 57. Surrounding the lead screw 57 is a square shaped outer tube 59 having one end secured to the motor mounting bracket 52. A square shaped inner tube 61 of slightly smaller dimensions than the outer tube 59 is telescoped in the other end of the outer tube 59 to move axially with respect thereto.

A flexible hose 63 extends through the hole 53 in the motor mounting bracket 52 and the hole 31 in the mounting bracket 25 and is secured within these holes with pegs 64 and 65, respectively. Similarly, a flexible hose 67 extends into the hole 54 of the motor mounting bracket 52 and the hole 32 of the bracket 25 and is secured therein with similar pegs 68 and 69, respectively. The hoses 63 and 67 provide flexible mounting means between the control assembly 35 and bracket 25 for purposes to bedescribed. The bracket 25 is positioned such that the lead screw 57, outer tube 59, and inner tube 61 extend generally parallel to the connecting rod 43, and parallel to and slightly in front of and beneath the housing 10.

Referring to FIG. 7, a nut 70 is mounted in the end of the inner tube 61 inside the outer tube 59. The nut 70 has internal threads that engage the lead screw 57.

A plug 71 (see FIG. 7) is mounted within the other end of the inner tube 61 and has a shank 72 extending outwardly away from the tube 61. A bracket 73 is suitably connected to theconnecting rod 43 to depend vertically therefrom and has a shank 75 extending toward and in axial alignment with the shank 72. A flexible hose 76 is connected between the shanks 72 and 75 such as by clamps 77 toprovide a flexible mounting between the control assembly 35 and the bracket 73 for purposes to be described. v

The motor 50 receives power through a suitable cable 85. Another cable 86 transmits signals to the motor 50 from a control network 87 shown schematically in FIG. 10, and which will hereinafter be described. The network 87 is contained within a circuit box 89 mounted to the front wall of the outer tube 59 near the motor 50. A series of conductors 90, through 94 connect the network 87 within the box 89 to a series of wiper arms 96 through 100, respectively. The conductors through 94 are preferably mounted'to the front wall of the outer tube 57 in the form of a printed circuit board 101.

Referring primarily to FIGS. 1, 2, and 7, an L-shaped bracket having an end wall 106 and' a front wall 107 is connected at its end wall 106 to the front wall of the inner tube 61 such as by screws 108. A code plate 1 10 see FIG; 9) is mounted to the inside surface of the front wall 107. I

The code plate 110 is made of a conductive material such as copper except for the cutout or aperture portions 1 11. The code plate 110 is coded by the apertures 111 in a sixteen bit gray code on a logarithmic scale as shown by the scale markings 113. The apertures form four horizontal rows having center lines 116, 117, 118,

and 119. Another center line marks a ground path.

The code plate 110 is mounted to the inner surface of the wall 107 such that as the inner tube 61 moves axi- 'in FIG. 1. The shoe control 127 includes a base 128 having an arm 129 that extends upwardly and rearwardly. A pie-shaped member 131 is pivotally mounted at 132 to the top of the base 128 just behind the arm 129. The pivotal member 131 has a round surface 133. A foot pedal 135 is pivotally attached at 137 near its bottom to the front of the base 128. A rod 139 has one end pivotally connected to the top of the pedal 135 and the other end pivotally connected to the side of the member 131, whereby operation of the pedal between the solid and dashed line positions of FIG. 1 causes the .member 131 to rotate about the pivot 132 between the 110, the gray code of the code plate l4l is arranged linearly as shown bythe scale markings 144.'The aper- 'tures 142 are arranged 'in four rows as shown by the center lines 146 through 149 with an additional center line 150 defininga ground path -just-'as with-the code plate 110. The code-plate 141 is mountedto the surface 133 with the left end of the code plateas viewed in FIG. 8 farthest from the arm 129. A series of five wiper arms 153 are mounted to the top of the. arm 1 29 and'electrii cally connected to suitable conductors within the'cable 125. The wiper, arms 153 are arranged to follow the center lines 146 through150 as the member l3l is pivoted by operation of the pedal 135. It ispreferable that the surface 1330f the member 131 and the inside surface of ,the L-shaped bracket 105 have raised portions which fit into the apertures llland 142 ofthe code plates 141 and 110, respectively, to providea smooth surface against which the wiper arms ride.

While electrical contacts orwiper arms and electrically conductive code plates have been describe'din this embodiment, other types of sensors could be used such as photosensitive or magnetic pickup devices for sensing the code readings off the code plates. i

In FIG. 10 there is shown a schematic diagram of the digital control network 87 of this invention. A gray code reading detected by the, wiper arms 153 inaccordance with their positions along the center lines 146 through; 150 of 'thecode plate 141, which reading corresponds to-one of sixteen possible readings from the code plate 141,-is' fed through the cable 125 to ag'ray to binary encoder 160. Output signals from-the encoder 160 representing .thebinary equivalent of the'gray code reading from the code plate 141 are fed through conductors 161' to one input of a comparator network 163.

A gray-code reading from the swell shade code plate 110,'detected by the wiper arms 96 through 100 and corresponding to. their relative positionalong the center lines 116 through 120 of the code plate 110, is fed through .the conductors 90 through 94 to. another gray to binary encoder 165. Output signals from the encoder 165 representing the binary equivalent of the gray code reading from the swell shade code plate 110 are fed through conductors 167t o another input of the comparator network 163. l

' The network 163 compares the signals at its inputs and produces a signal at an output conductor 171 if the signals at its input 161 represent a primary code readinggreater than the binary code reading represented by the signals at its input 167, and a signal at an output signals Onthe conductor 167, a signal is generated atductor 179 to one side of an AC power source 180,and the relay 176 has-another input connected by a conductor 181 and the conductor l79fto the same side of the AC power source 180. The otherfside of the 'power source 180 is connected by aconduc'tor 183 to suitable windings of the rnotor'50. v When asignal appears at-the eoridlg ctor 171 to operate the relay 175, a signalis fed from the output of the relay 175 through conductor 1 to a suitable winding of the motor 50 to drive the motor 50 me direction'so as to openthe swellshades14 and 15.

When a signal appears at the conductor 173 to operate the relay 176, a signal isffed from the output of the relay176 througha conductor 1 87 to a suitable windingof the motor 50 to drive 'themotor'in a'direction' so as to close the swell shades 14 and'15.

a I a OPERATION 7 Suppose that as an initial conditiontheswell shades l4 and 15 are closed so t'hat 'the. innertube 61 vis tele scoped all the way out with the wiperarms 96 through 100 contacting the codefplate at "a location generallyadjacem the extreme left-hand marking of the scale 113. Also, in this initial condition the foot pedal is in its upp ermost'positio'n shown by solid lines in FIG. 1 so that "the wiper. arms 153contact the code plate 141 ata location generally adjacent thefar left-hand mark of the scale 144. Suppose now that the organist wishes to open the swellshades 14 and 15a prescribed amount which from his experience corresponds to depressing the foot pedal l35 azprescrib ed amount. When the footpedal 135 is depressed, the

pivotal member 131 is' rotated about the point 132 causing the code plate 141 to move relative to the :wiper arms 153.1At the final foot pedal position selected by theorganist lthe wiper arms 153 are located along the center'lines146 through adjacent some mark of the scale 144. This'lo'cationcorresponds to one of l6 gray code readings. Signals corresponding to the selected reading are fed through the conductors 125 to thenetwork 87 in thebox 57.Specifically,these signals are fed to the gray to binary encoder which converts these signals-tea binarycode reading. The output of the encoder 160 is thenifed'to one input of the comparator163 Y y Meanwhile, signals corresponding to the initial condition gray codereading detectedby the wiper arms 96 through 100 on the code plate 110 are fedthrough the conductors 90 through 94 to the network 87 and specifically to the gray to binary encoder 165. The encoder 165 converts the gray code reading to binary code signals, which signals are fed through the conductor 167 to another input of the comparator 163.

Since the signals on the conductor 1 61 represent a binary number greater than that represented by the inner, tube 61 further into .the outer tube 59 by means i of the lead screw 57turni'ng within the threaded nut 70. If the lead screw 57 and nut 70 have right-hand threads,

the motor 50 is wired to'drive in a counterclockwise direction as viewed in FIG. 3. This in turn pulls the con-.

necting rod 43 to the left through the ho'se'connectionv 76 and vertical bracket 73, which further causes'the brackets 37 and 38 to pivot clockwise about the points 18 and 19 to thereby open the swell shades 14 and 15. As the inner tube 61 moves to the left, so also does the code plate 110 so that the wiper arms 96 through 100 sense progressively higher code readings from the code plate 110. I I v The motor 50v continues to drive, and hence the swell shades 14'and 15 continue to open, until the wiper arms 96 through 100 locate with respect to the code plate 110 at a position along the scale 113 corresponding to a gray code reading equal to that detected by the wiper arms 153 of the shoe assembly 127. When this occurs, the numbersrepresented by the signals at the inputs of the comparator 163 are equal, the signals on both the output conductors 171 and 173 become zero, and the motor 50 stops.

Since as the brackets 37 and 38 pivot about the points 18 and 19in an arcuate path, the connecting rod 43, the vertical bracket 73, and hence the outer and inner tubes 59 and 61 must be capableof swinging slightly forward of the swell shade enclosure as the swell shades are actuated. The flexible hose mountings 63, 67, and 76 provide sufficient-flexibility to allow for this slight forward movement.

v If the organist desires nowto close the swell shades 14 and some prescribed amount, he simply releases the foot pedal 135 to a position which he knows from experience corresponds to the desired swell shade 4 through 100are detecting the higher gray code reading of the previous swell shade position, the signals on the conductor 167 now represent a number greater than the signals on the conductor 161 to produce a signal on the output conductor 173 of the comparator 163. The signal on the conductor 173 operates therelay 176 causing the motor 5010 drive in the opposite direction. This in turn causes the inner tube 61 and the connecting rod 43 to move to the right further closing the swell shades 14 and 15; The motor 50 continues to drive until the gray code reading detectedby the wiper arms 96 through 100 onthe code plate 110 is equal to the reading detected by the wiper arms 153 of the shoe assembly 127, at whichtime the numbers represented by I the signals at the inputs of the,comparator 163 are equal and the motor 50 stops.

, In this manner operation of the foot pedal 135 will locate the swell shades 14 and 15 at any one of 16 positions between fully closed and fully opened. It is, of course, within the scope of this invention to increase or decrease the total number of possible positions by increasing or decreasing the code markings of the code plates 141 and 110 and designing the circuit 87 to handle a corresponding number of bits.

One of the features ofthis invention is the use of the logarithmic scale for the gray code of the code plate 110 and a linear scale for the gray code of the code plate 141. Toward the closed condition of the swell shades, relatively small changes in swell shade opening orv closing produce significant changes in sound volume, while toward the open condition .of the swell shades, relatively large changes in swell shade opening or closing are required to produce the same change in sound volume. It has been found'that the relationship of swell shade opening to sound volume is generally logarithmic. With the code. plate coded on a logarithmic scale, as the pedal is moved one increment near its fully closed positiom-the corresponding change in swell shade opening is relatively small, but as the foot pedal 135 is moved I that same increment further toward its fully opened position, the corresponding change in swell shade opening is greater in accordance with the'logarithmic scale 113. In this way linear operation of the pedal 135 produces linear changes in sound volume.

In FIG. 11 there is shown another embodiment. of

this invention. Here the motor 50 and'lead screw 57 arsecured at its corner 193 to a stationary mount 194,

pivotally connected at its upper end 196 to the shaft through a slot 197, and pivotally connected at its other end 199 to the upper end of a rod 200 The lower end of the rod 200 is pivotally. connected at 202 to the top of an air bellows 203 near its open side. The bottom of the bellows 203 is secured to a solid mounting 204. The bottom and top of the; bellows are pivotally connected at 206. A weight 208 is mounted on the top of the bellows 203 near its open side to bias the bellows closed. t

A suitable source of compressed. air (not shown) is connected to a conduit 210 which feeds the'air to the input of an intake valve 212. The-output of 'the'intake valve 212 is connected bya conduit 214 to the inner chamber of the bellows 203. The inner chamber of the bellows 203 is also connectedby a conduit 216 to the input of an exhaust valve 218, the outputof which is connected to an exhaust conduit 220. The valves 212 and 218 are operated by electrical solenoids 222 and 223, respectively. Thesolenoids 222 and 223 would be operated in the same manner as the motor 50, and would therefore replace the motor 50 in the network 87.

Hence, when a signal appears at the output conductor 171 of the comparator 163, the solenoid 223 is energized to open the valve 218,- exhausting air from the bellows 203, closingthe bellows 203 an amount corresponding to the positions of the wiper arms with respect to the code plates. This in turn moves the shaft 190 to the left to open the swell shades l4 and 15. Conversely, when a signal appears at the output conductor 173 from the comparator 163, the solenoid 222 is energized to open the valve 212, forcing air into the bellows 203, to open the bellows an amount corresponding to the relative positions of the wiper arms with respectto the code plates. Opening the bellows in turn moves the shaft 190 to the right and closes the swell shades l4 and Just as with the first-described embodiment, the amount of opening or closing of the swell shades is determined by the position of the pedal 135.

Certainly, further variations can be made on these embodiments and still bewell within the scope of' this invention. For example, instead of the bellows 2030f the embodiment of FIG. 11', the shaft 190 could be operated by the piston of an air Cylinder or a hydraulic cylinder which in turn would be operated by suitable valves, similar to the valves 212 and 218, and solenoids similar to the solenoids 222 and 223. The network 87 would operate in each of these variations as heretofore described. i v I I Various changes and modifications may be made in this invention, as will be readily apparent to those skilled in the.art.'Such changes and modifications are within the scope and teaching of this invention as defined by the claims appended hereto.

.What is claimed is: t

1 A swell shade control comprising an actuator means, means for connecting the actuator meansto the swell shades such that actuation of the actuator means in'onedirection opens the shades and actuation of the actuator means inthe opposite directioncloses. the shades, an electrical, network, a command means, means responsive to' the command means fortransmitting first signals to thenetwork representing a' final swell shade position,.means responsive to the' position of; the swell shades for transmittingsecond-signals to the networkrepresenting the instantaneous position of the shades, means associated with the network for generating one control signal when the first and second signals compare in one manner of predetermined correspondence,-means associated with the network for generating another control signalwhen the first and second signals compare in another manner of predetermined correspondence, and means responsive to the control signals for actuating the actuatormeans in a direction to move the swell shades toward the final position.

,2. The swell shade control of claim 1 wherein the first and second signals represent digital code readings.

,3. The swell shade control of claim 2 wherein one control signal is generated when the first signals represent a digital code reading greater than the digital code reading represented by the second signals, and the other control signal is generated when the second signalsrepresent a digital code reading greater than the digital code reading represented by the first signals.

4. The swell shade control of claim 1 whereinv the command means comprises a swell shoe having a base and a movable pedal, and means for generating the first signals in response to the position of the pedal.

5. The swell shade control of claim 1 further com-- prising a first code plate associated with the command means having a digital code thereon, first detector means for detecting a selected code reading from the code plate, means responsive to the first detected code reading to generate the first signals, a second code plate associated with the actuator means having a digital code thereon, a second detector means, means for mounting the second detector means and second code plate for detecting a code reading on the second code plate corresponding to the instantaneous position of the shades, and means responsive to the second detected code reading for generating the second signals.

6. The swell shade control of claim 5 wherein the command means comprises a swell shoe having a base and a movable pedal mounted thereto, and further comprising means for mo'unting the'first code plate and first detector means on the swell shoe for detection by the first detector means of code readings on the first code plate corresponding to pedal positions.

7., The swelljshad'e'control of claim 5 wherein the code on the first code plateis'generally linear and the code on the'second code plate is generally logarithmic.

8. The swell shade control ofclaim' l]whereinthe actuating means comprises an electric motor, a lead screw mounted 'to the shaft-of the electric motor,

means responsive to rotationa-of the lead screw in one direction to open the shades, and means responsive to rotation of the lead screw ,in the opposite direction to close the shades. v t

9. The swellshade controlof claim 8' further comprising a first code plate associated with the command means having a digital code thereon, first detector meansfordetecting a selected code reading from the code plate, means responsive to the firstdetected code reading to generate the first signals, a second code plate associated with the actuator means having a I digital code thereon,fa seconddetector means, means for'mounting the second detector means and second code plate for detectinga code reading o th Second code plate corresponding to the instantaneous position of the shades, and means responsive to the second detected code reading for generating the secondsignals.

10. The swellshade control of claim 9 further comprising a first tube surrounding the lead screw in fixed relation thereto, a secondtube mounted for telescoping movement in relation to the first tube, means responsive to rotation of the lead screw, in one direction to extend the second'tube with respect to the first tube, means responsive to rotation of the lead screwin the opposite direction to retract the second tube'with respect to the first tube, means for closing the shades in response to movement of the second tube in one of the second tube relative to the seconddetector means.

12. The swell shade control of claim 9 wherein the v first and second detector means are electrical contacts,

and the surfaces of the first andsecond code plates are electrically coded along their lengths, and further including means for mounting the contacts of the first detector means to contact the coded surface of the first code plate producing electrical signals at the first contacts representing a digital code reading corresponding to a position along the length of the first code plate, and means for mounting the contacts of the second detector means to contact the coded surface of the second code plate producing electrical signals at the second contacts representing digital code readings corresponding to positions along the lengths of the second code plate. I

13, The swell shade control of claim 9 wherein the command means comprises a swell shoe having a base and a movable'pedal mounted thereto, and further comprising means for mounting the first code plate and first detector means on the swell shoe for detection by means for exhausting air from the bellows in response to the other control signal, and means to ,open and close the shades in response to operation of the bellows. v 

1. A swell shade control comprising an actuator means, means for connecting the actuator means to the swell shades such that actuation of the actuator means in one direction opens the shades and actuation of the actuator means in the opposite direction closes the shades, an electrical network, a command means, means responsive to the command means for transmitting first signals to the network representing a final swell shade position, means responsive to the position of the swell shades for transmitting second signals to the network representing the instantaneous position of the shades, means associated with the network for generating one control signal when the first and second signals compare in one manner of predetermined correspondence, means associated with the network for generating another control signal when the first and second signals compare in another manner of predetermined correspondence, and means responsive to the control signals for actuating the actuator means in a direction to move the swell shades toward the final position.
 2. The swell shade control of claim 1 wherein the first and second signals represent digital code readings.
 3. The swell shade control of claim 2 wherein one control signal is generated when the first signals represent a digital code reading greater than the digital code reading represented by the second signals, and the other control signal is generated when the second signals represent a digital code reading greater than the digital code reading represented by the first signals.
 4. The swell shade control of claim 1 wherein the command means comprises a swell shoe having a base and a movable pedal, and means for generating the first signals in response to the position of the pedal.
 5. The swell shade control of claim 1 further comprising a first code plate associated with the command means having a digital code thereon, first detector means for detecting a selected code reading from the code plate, means responsive to the first detected code reading to generate the first signals, a second code plate associated with the actuator means having a digital code thereon, a second detector means, means for mounting the second detector means and second code plate for detecting a code reading on the second code plate corresponding to the instantaneous position of the shades, and means responsive to the second detected code reading for generating the second signals.
 6. The swell shade control of claim 5 wherein the command means comprises a swell shoe having a base and a movable pedal mounted thereto, and further comprising means for mounting the first code plate and first detector means on the swell shoe for detection by the first detector means of code readings on the first code plate corresponding to pedal positions.
 7. The swell shade control of claim 5 wherein the code on the first code plate is generally linear and the code on the second code plate is generally logarithmic.
 8. The swell shade control of claim 1 wherein the actuating means comprises an electric motor, a lead screw mounted to the shaft of the electric motor, means responsive to rotation of the lead screw in one direction to open the shades, and means responsive to rotation of the lead screw in the opposite direction to close the shades.
 9. The swell shade control of claim 8 further comprising a first code plate associated with the command means having a digitAl code thereon, first detector means for detecting a selected code reading from the code plate, means responsive to the first detected code reading to generate the first signals, a second code plate associated with the actuator means having a digital code thereon, a second detector means, means for mounting the second detector means and second code plate for detecting a code reading on the second code plate corresponding to the instantaneous position of the shades, and means responsive to the second detected code reading for generating the second signals.
 10. The swell shade control of claim 9 further comprising a first tube surrounding the lead screw in fixed relation thereto, a second tube mounted for telescoping movement in relation to the first tube, means responsive to rotation of the lead screw in one direction to extend the second tube with respect to the first tube, means responsive to rotation of the lead screw in the opposite direction to retract the second tube with respect to the first tube, means for closing the shades in response to movement of the second tube in one direction, and means for opening the shades in response to movement of the second tube in the reverse direction.
 11. The swell shade control of claim 10 wherein the second code plate is mounted to move with movement of the second tube relative to the second detector means.
 12. The swell shade control of claim 9 wherein the first and second detector means are electrical contacts, and the surfaces of the first and second code plates are electrically coded along their lengths, and further including means for mounting the contacts of the first detector means to contact the coded surface of the first code plate producing electrical signals at the first contacts representing a digital code reading corresponding to a position along the length of the first code plate, and means for mounting the contacts of the second detector means to contact the coded surface of the second code plate producing electrical signals at the second contacts representing digital code readings corresponding to positions along the lengths of the second code plate.
 13. The swell shade control of claim 9 wherein the command means comprises a swell shoe having a base and a movable pedal mounted thereto, and further comprising means for mounting the first code plate and first detector means on the swell shoe for detection by the first detector means of code readings on the first code plate corresponding to pedal positions.
 14. The swell shade control of claim 1 wherein the actuating means includes a bellows, means for applying air to the bellows in response to one control signal, means for exhausting air from the bellows in response to the other control signal, and means to open and close the shades in response to operation of the bellows. 